Naphthol sulfonamidonaphthalides

ABSTRACT

This invention relates to a class of indicator dyes useful as optical filter agents in photographic processes to protect a selectively exposed photosensitive material from further exposure during processing in the presence of incident light. Such dyes comprise 3,3-disubstituted 6-sulfonamido naphthalides wherein the 3,3 substituents are p-hydroxynaphthyl radicals.

United States Patent Simon July 1, 1975 NAPHTHOL [56] References Cited SULFONAMIDONAPHTHALIDES UNITED STATES PATENTS [75] Inventor: Myron S. Simon, West Newton, 3,772,339 11/1973 Greenwald 260/3432 Mass. [73] Assignee: Polaroid Corporation, Cambridge, Primary Examiner john F Mass Attorney, Agent, or FirmSyb1l A. Campbell [22] Filed: Mar. 14, 1974 [57] ABSTRACT App! 451377 This invention relates to a class of indicator dyes use- Related US. Application Data Continuationin-part of Ser. No. 193,746, Oct. 29, 1971, Pat. No. 3,811,881.

US. Cl. 260/3431 R; 96/27 E; 252/300 Int. Cl C07d 7/20 Field of Search 260/3432 R ful as optical filter agents in photographic processes to protect a selectively exposed photosensitive material from further exposure during processing in the presence of incident light. Such dyes comprise 3,3- disubstituted 6-sulfonamid0 naphthalides wherein the 3,3 substituents are p-hydroxynaphthyl radicals.

7 Claims, 1 Drawing Figure 1 NAPHTI-IOL SULFONAMIDONAPHTHALIDES CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of my copending application Ser. No. 193,746 filed Oct. 29, 1971, now US. Pat. No. 3,811,881.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to novel chemical compounds, and more specifically, it relates to a new class of indicator dyes. In a particular aspect it relates to certain naphthalides useful as optical filter agents in photographic processes for protecting an exposed photo sensitive material from post-exposure fogging during development in the presence of extraneous incident light and to such photographic uses.

2. Description of the Prior Art A number of photographic processes by which images may be developed and viewed within seconds or minutes after exposure have been proposed. Such processes generally employ a processing composition which is suitably distributed between two sheet-like elements, the desired image being carried by one of said sheet-like elements. The resulting images may be in blackand-white, e.g., in silver, or in one or more colors. Processing may be conducted in or outside of a camera. The most useful of such processes are the diffusion transfer processes which have been proposed for forming silver or dye images, and several of these processes have been commercialized. Such processes have in common the feature that the final image is a function of the formation of an image-wise distribution of an im age-providing reagent and the diffusion transfer of said distribution to or from the stratum carrying the final image, whether positive or negative.

US. Pat. No. 3,415,644 discloses a composite photo sensitive structure, particularly adapted for use in reflection type photographic diffusion transfer color processes. This structure comprises a plurality of essential layers including, in sequence, a dimensionally stable opaque layer; one or more silver halide emulsion layers having associated therewith dye image-providing material which is soluble and diffusible, in alkali, at a first pH, as a function of the point-to-point degree of its associated silver halide emulsions exposure to incident actinic radiation; a polymeric layer adapted to receive solubilized dye image-providing material diffusing thereto; a polymeric layer containing sufficient acidifying capacity to effect reduction of a processing composition from the first pH to a second pH at which the dye image-providing material is substantially nondiffusible; and a dimensionally stable transparent layer. This structure may be exposed to incident actinic radiation and processed by interposing, intermediate the silver halide emulsion layer and the reception layer, an alkaline processing composition providing the first pH and containing a lightreflecting agent, for example, titanium dioxide to provide a white background. The light reflecting agent (referred to in said patent as an opacifying agent") also performs an opacifying function, i.e., it is effective to mask the developed silver halide emulsions and also acts to protect the photoexposed emulsions from postexposure fogging by light passing through the transparent layer if the photoexposed film unit is removed from the camera before image forma tion is complete.

In a preferred embodiment, the composite photosensitive structure includes a rupturable container, retaining the alkaline processing composition having the first pH and light-reflecting agent, fixedly positioned extending transverse a leading edge of the composite structure in order to effect, upon application of compressive pressure to the container, discharge of the processing composition intermediate the opposed surfaces of the reception layer and the next adjacent silver halide emulsion.

The liquid processing composition distributed intermediate the reception layer and the silver halide emulsion, permeates the silver halide emulsion layers of the composite photosensitive structure to initiate development of the latent images contained therein resultant from photoexposure. As a consequence of the development of the latent images, dye image-providing material associated With each of the respective silver halide emulsion layers is individually immobilized as a function of the point-to-point degree of the respective silver halide emulsion layer photoexposure, resulting in imagewise distributions of mobile dye image-providing materials adapted to transfer, by diffusion, to the reception layer to provide the desired transfer dye image. Subsequent to substantial dye image formation in the reception layer, a sufficient portion of the ions of the alkaline processing composition transfers, by diffusion, to the polymeric neutralizing layer to effect reduction in the alkalinity of the composite film unit to the second pH at which dye image-providing material is substantially nondiffusible, and further dye imageproviding material transfer is thereby substantially obviated.

The transfer dye image is viewed, as a reflection image, through the dimensionally stable transparent layer against the background provided by the reflecting agent, distributed as a component of the processing composition, intermediate the reception layer and next adjacent silver halide emulsion layer. The thus-formed stratum effecitvely masks residual dye image-providing material retained in association with the developed silver halide emulsion layer subsequent to processing.

In the copending US Pat. application Ser. No. 786,352 of Edwin H. Land, filed Dec. 23, 1968, now abandoned, and Ser. No. 101,968 filed Dec. 28, 1970, now US. Pat. No. 3,647,437, in part a continuation of Ser. No. 786,352, an organic light absorbing reagent (or optical filter agent), such as a dye, which is present as a light-absorbing species at the first pH and which may be converted to a substantially non-light-absorbing species at the second pH is used in conjunction with the light-reflecting agent to protect the selectively exposed silver halide emulsions from post-exposure fogging when development of the photoexposed emulsions is conducted in the presence of extraneous incident actinic radiation impinging on the transparent layer of the film unit.

In copending US. Pat. application Ser. No. 103,392 filed Jan. 4, 1971, now US. Pat. No. 3,702,245, pH- sensitive dyes derived from certain hydroxy-substituted carbocyclic aryl compounds, viz., particular phenols and naphthols are disclosed as useful as optical filter agents for absorbing incident radiation actinic to selectively exposed photosensitive materials within a predetermined wavelength range in the longer wavelength region of the visible spectrum. Certain of the novel dyes disclosed therein comprise the subject matter of the present invention, namely, l-naphthol naphthaleins possessing a sulfonamido substituent on the naphthalide portion of the dye.

SUMMARY OF THE INVENTION It is, therefore, the primary object of the present invention to provide novel indicator dyes.

It is another object of the present invention to provide a novel class of indicator dyes useful as optical filter agents in photographic processes for preventing post-exposure fogging of a selectively exposed photosensitive material during development in the presence of incident light.

It is a further object of the present invention to provide products, compositions and processes for the development of photosensitive materials in which the novel indicator dyes are used.

Other objects of this invention will in part be obvious and will in -part appear hereinafter.

The invention accordingly comprises the processes involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products and compositions possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

According to the present invention, there is provided a novel class of dyes derived from l-naphthols which contain as the ring-closing moiety, a naphthalide substituted in the 6-position with a sulfonamido group.

The indicator dyes of the present invention, like phthalein indicators in general, such as phenol phthalein and l-naphtholphthalein, possess spectral absorption characteristics which are reversibly alterable in response to changes in environmental pH. These dyes possess a highly colored form capable of absorbing visible radiation in alkaline media at a first pH value above their respective pKa and a substantially colorless form, i.e., a form which is substantially non-light-absorbing in the visible spectrum in less alkaline media at a second pH value below their respective pKa. By pKa is meant the pH at which about 50% of the dye is present in its light-absorbing form and about 50% is present in its non-light-absorbing form.

It will be appreciated that such compounds will find utility in titrations and other analytical procedures where phthalein indicator dyes are commonly employed, for example, to measure changes in pH value as reflected by the change in color of the dye from one color to another or from colored to colorless or vice versa. The indicator dyes of the present invention, however, because of their particularly broad absorption spectrum in the visible region are useful as optical filter agents in photographic processes where development of a selectively exposed photosensitive material is performed at least in part outside the confines of a camera in the presence of extraneous incident actinic radiation.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawing.

4 BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a graphic illustration of the spectral absorption characteristics of a l-naphthol naphthalein of the present invention as compared to the same naphthalein without the sulfonamido substituent on the ringclosing moiety and represents the optical transmission density, i.e., absorbance of the respective dyes measure on a logarithm scale over the wavelength range of 350 nm. to 750 nm. in aqueous alkaline solution at a pH substantially above their pKa.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, it has been found that a sulfonamido group substituted on the naphthalide portion of l-naphthol naphthaleins broadens the absorption spectrum of the dye towards the shorter wavelength region of the visible spectrum. Because of the broader overall spectral absorption of these dyes in the visible wavelength range, they find particular utility as optical filter agents in photographic processes for protecting photosensitive materials from extraneous incident light. Moreover, the sulfonamido group offers a convenient means of introducing a bulky substituent, such as, a long chain alkyl substituent for rendering the dye substantially non-diffusible in the processing solution in order to achieve optimum efficiency as a radiation filter and to prevent diffusion of optical filter agent into layers of the film unit where its presence may be undesirable.

The novel class of indicator dyes of the present invention may be defined as 3,3-disubstituted-6-sulfonamido-naphthalides wherein the 3,3 substituents are p-hydroxy-naphthyl radicals. Such dyes may be represented by the formula:

wherein A and B represent 4'-hydroxy-l '-naphthyl radicals, the same or different, and R is selected from alkyl, aryl, aralkyl and alkaryl.

The R group usually contains up to about 20 carbon atoms but may contain a greater number of carbon atoms as may be desired, for example, to adjust the diffusibility of the dye in aqueous solution. The alkyl group or the alkyl portion of the alkaryl or aralkyl group may be branched or straight chain, and preferably is straight chain where the sulfonamido group is being utilized to render the dye substantially nondiffusible in the processing solution. Examples of groups that may comprise R include alkyl, such as, methyl, ethyl, propyl, isopropyl, sec-butyl, tert-butyl, hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl and eicosanyl; aryl, such as, phenyl and naphthyl; and aralkyl and alkaryl, preferably, phenyl-substituted alkyl and alkyl substituted phenyl, such as, benzyl, phenethyl, phenylhexyl', p-hexylphenyl, p-octylphenyl and pdodecylphenyl.

The indicator dyes defined above and as represented in the foregoing formula may contain additional substituents, e.g., on one or both of the A and B radicals as may be desired which do not interfere with the function of the dye for its selected ultimate use. Typical substituents include alkyl, such as, methyl, ethyl, isopropyl, n-butyl, t-butyl, hexyl, oetyl, dodecyl, hexa decyl, octadecyl and eicosanyl; aryl, such as, phenyl, 2-hydroxyphenyl, and naphthyl; aralkyl and alkaryl, such as, benzyl, phenethyl, phenylhexyl, p-octylphenyl, p-dodecylphenyl; alkoxy, such as, methoxy, ethoxy. butoxy, l-ethoxy-2(fl-ethoxyethoxy), dodecyloxy and octadecyloxy; aryloxy, such as phenoxy, benzyloxy, naphthoxy', alkoxyalkyl, such as methoxyethyl, dodecyloxyethyl; halo, such as, fluoro, bromo, and chloro; trifluoralkyl, such 'as, trifluoromethyl, mono" and bistrifluoromethyl earbinol, sulfonamido; sulfamoyl; acyl and its derivatives; aminomethyl; amido; sulfonyl; sulfo; cyano; nitro; amino including monoand disubstituted amino, e.g., N-ethyl dimethylamino; carboxy; and hydroxyl. In addition to the above, the substituent may comprise a fused ring. For example, the A and/or 8 radical may contain as a substituent, a cycloaliphatic or an aromatic ring usually having 5 or 6 members, carbocyclic or heterocyclic and substituted or unsubstituted, bonded to adjacent carbon atoms. 7

For use as optical filter agents in photographic processes, such as, diffusion transfer processes employing highly alkaline processing solutions, it may be desirable that the indicator dye selected as the optical filter agent possess a relatively high pKa so that the dye will be in a light-absorbing form during the initial stages of processing and yet may be rendered substantially non-light absorbing within a relatively brief interval as the pH subsequent to substantial image formation is reduced in order to permit early viewing of the image. Simple lnaphthol naphthaleins have a comparatively low pKa. For example, lnaphthol naphthalein has a pKa of about 8.5, where it is desired to raise the pKa, a hydrogen-bonding group may be substituted on one or both of the p-hydroxynaphthyl radicals adjacent to the functional OH.

As an illustration, in Formula (I) above, the A radical may comprise wherein one of R and R is a hydrogen-bonding group and the other is hydrogen, or the A and B radicals may comprise 1 OH R R and R amino and N,N-

6 Pat. application Ser. No. 103,865 filed Jan. 4, 1971, now US. Pat. No. 3,833,614.

As the R, R, R and R group, any hydrogenbonding group may be used that is capable of raising the pKa. The association of two atoms through hydrogen to form a hydrogen bond between or within molecules is well known. When hydrogen is attached to an electronegative atom, for example, 0 or N, the resultant bond is polarized. lf directed toward another atom (M) with an unshared pair of electrons, the hydrogen acts as a bridge between the atoms (OH...M) due to the electrostatic attraction to both atoms between which the hydrogen proton can be transferred. In the above compounds an intramolecular hydrogen bond is formed between the p-hydroxy group and the adjacent hydrogen-bonding'group, Le, a group containing a heteroatom possessing an active unshared pair of electrons, such as, O, N, S or halogen, e.g., F., which has a free electron pair or a negative charge in basic solution and which is capable of forming a 5-, 6- or 7- membered and preferably a 5- or 6-membered hydrogen-bonded ring with the p-hydroxy group. Preferably, the heteroatom in the hydrogen-bonding group has attached to it a proton which is more acidic than the pro' ton on the naphtholic OH and ionizes in basic solution to a negative charge. Such groups include, for example, carboxy; hydroxy; o-hydroxyphenyl; bis trifluoromethyl carbinol; sulfonamido (-NHSO -R') and sulfamoyl (SO ,NH-R") wherein said R and R" have the same meaning given for R. Suitable R and R" substituents include branched or straight chain alkyl, e.g., methyl, ethyl, isopropyl, n-butyl, t-butyl, hexyl, octyl, dodecyl, hexadecyl, octadecyl and eicosanyl; aryl, e.g., phenyl and naphthyl; aralkyl and alkaryl, e.g., benzyl, phenethyl, phenylhexyl, p-octyphenyl and pdodecylphenyl,

In a preferred embodiment, the compounds of the present invention may be represented by the formula:

wherein R, R R and R each are selected from hydrogen and a hydrogen-bonding group forming a 5-, 6- or 7-membered intramolecular hydrogen-bonded ring with the adjacent -OH and being a member selected from hydroxy, carboxy, o-hydroxyphenyl, sulfonamido, sulfamoyl and his trifluoromethyl earbinol, at least one of R and R and at least one of R and R being hydrogen, and R is selected from alkyl, aryl, aralkyl and alkaryl. In a particularly preferred embodiment, R and R are hydrogen and at least one of R and R is a hydrogen-bonding group. Where both R and R are hydrogen-bonding groups, they may be the same or different.

Specific examples of naphthol indicator dyes within the scope of the present invention are as follows:

Various methods have been employed in the synthesis of phthaleins and naphthaleins, for example, by reacting naphtholic anhydride with the selected 1- naphthol or by reacting a naphthalide intermediate with the selected l-naphthol to form the complete dye.

or potassium salt which is oxidized to yield the bis-(3 carboxy-4'-hydroxynaphthyl)-6-aminonaphthalide. The 6-aminonaphthalide is then reacted with the selected sulfonyl chloride (RSO Cl) to yield the 6- sulfonamidonaphthalide product.

The following Example is given to further illustrate the present invention and is not intended to limit the scope thereof.

EXAMPLE Preparation of the compound of formula (4):

A. 13.1 g. of potassium nitrate was dissolved in ml. of sulfuric acid. This solution was added dropwise to a cooled (5, C.) solution of 23.8 g. of naphthalaldehydic acid in ml. of sulfuric acid, while maintaining the temperature at 50C. throughout addition. The reaction mixture was refrigerated overnight. It was then poured into ice water (about 400 m1.). A light yellow solid was obtained. The solid was dissolved in about 500 ml. of 1,2-dimethoxyethane, and after evaporating the solvent down to about half the volume, 3-hydroxy- 6-nitronaphthalide-l,8 was obtained beige crystals.

B. A mixture of 3-hydroxy-6-nitronaphthalide-l,8 (6.12 g.; 0.025 m.) prepared above and l-hydroxy-2- naphthoic acid (4.7 g.', 0.025 m.) in 100 ml. of 12% p-toluenesulfonic acid in acetic acid solution was heated to reflux. After about one hour the reactants were in solution and then a yellow solid formed. After refluxing for an additional two hours, the reaction solution was cooled, and the yellow solid was removed by filtration and recrystallized from methyl cellosolve to yield 8.3 g. (67% by weight) of 3-(3'-carboxy-4'- hydroxynaphthyl )-6-nitronaphthalidel ,8, melting range 255258C.

C. 3( 3 '-carboxy-4'-hydroxy-l naphthyl)-6- nitronaphthalide-l.8 (4.15 g.; 0.01 m.) as prepared in step (B) was heated in 120 ml. of methyl cellosolve until the naphthalide was dissolved. The resulting solution was cooled to room temperature. Stannous chloride (6.78 g.; 0.03 m.) dissolved in hydrochloric acid (20 ml.) was added dropwise to the solution, and the solution was stirred overnight at room temperature. The reaction mixture was poured into ethyl acetate (about 250 ml.) and the ethyl acetate solution extracted several times with water until some orange solid precipitated. Then the ethyl acetate was removed by evaporation leaving an orange oil that crystallized upon standing to yield 2.5 g. of the corresponding 6- aminonaphthalide. (65% by weight yield).

D. The 3-(3'-carboxy-4-hydroxy-l-naphthyl)-6- aminonaphthalide-1,8 prepared above (4.8 g.; 0.012 m.) and l-hydroxy-2naphthoic acid (4.5 g.; 0.024 m.) were added to a deareated aqueous sodium hydroxide solution (7.6% NaOH) under nitrogen. The resulting solution was heated to 70C. for five hours after which time no aminonaphthalide remained. the solution was then poured into water and extracted several times at pH 8-10 with ethyl acetate to remove any remaining 1- hydroxy-Z-naphthoic acid and at pH 6-8 to remove other impurities. The pH was then adjusted to below pH 6 by the addition of 10% aqueous hydrochloric acid. The solution was extracted with ethyl acetate and upon evaporation of the solvent, 4.95 g. of leuco compound was obtained (67.57( by weight yield).

E. To the leuco compound prepared above (9.5 g.; 0.017 m.) in 500 ml. of dimethylsulfoxide under nitro gen, was added portionwise a 50% solution of sodium hydride (4.1 g.-, 0.017 m.) in oil. The mixture was heated to 60C. for one hour until no more reaction was apparent. After cooling to room temperature, silver acetate (100 mg.) was added and then potassium persulfate (4.6 g.). Upon heating for minutes, the mixture turned blue. The reaction mixture was then filtered over Celite. and ice water was added to the filtrate which was acidified with dilute hydrochloric acid. The flocculent beige solid that formed was extracted with ethyl acetate several times. The first two extracts yielded a small amount of grey solid impurity. Further extractions, upon evaporation of the ethyl acetate, gave a brown oil which when taken up in methanol and with water added yielded the corresponding naphthalide compound as a yellow solid (6.5 g.; 68.4% by weight yielded).

F. 2.30 g. of 3,3-bis-(3'-carboxy-4-hydroxy-1 naphthyl)-6-amino-naphthalide of step (E) was dissolved in water (25 ml.) and 1N aqueous sodium hy droxide solution (6 ml.). Acetone (10 ml.) was added and a combination pH electrode inserted. The pH was adjusted to 8.5 by adding 1N sodium hydroxide. The solution was stirred and para-n-dodecylbenzenesulfonyl chloride (1.40 g.) was added. The mixture was warmed to 40C., and stirring was continued. The pH which had slowly dropped to about 7.5 was adjusted to 8.5 by adding 1N sodium hydroxide solution. The mixture was stirred overnight under nitrogen at 40C. The pH which had dropped to about 3.5 was adjusted to 8.5 with 1N sodium hydroxide and an additional 0.70 g. the sulfonly chloride was added. Reaction was continued for about 8 hours with the pH reading held between 7.5 and 8.5. The mixture was then cooled and filtered to remove a crystalline solid. The filtrate was diluted with ml. of water and mixed with 100 ml. of ethyl acetate. The pH of the mixture was adjusted to 7.0 with dilute hydrochloric acid. The layer were separated and the lower layer was stirred with 100 ml. of fresh ethyl acetate and the pH was adjusted to 6.0. The ethyl acetate layer was separated, washed with dilute hydrochloric acid and then washed with water. The ethyl acetate solution was dried over magnesium sulfate; filtered and evaporated to give the title compound (0.60 g.)

It will be appreciated that other naphthols may be substituted for 2-carboxy-l-naphthol in the foregoing procedure to yield the desired naphthol 6- sulfonamidonaphthalide indicator dye product. Illustrative naphthols include 8-substituted-l-naphthols, such as, 1,8-naphthalenediol, 8-carboxy-1-naphthol and 8-dodecylsulfonamido-l-naphthol and 2-substituted-l-naphthols, for example. Z-bis trifluoromethyl-L naphthol, 2-n-propylsulfamoyl-l-naphthol, and 2 hexylsulfonamido-l-naphthol. Also, other sulfonyl chlorides may be substituted for para-n-dodecylbenzenesulfonyl chloride in the foregoing procedure, for example, RSO- ,Cl wherein R is phenyl, n-octadecyl and phenylhexyl.

The spectral absorption characteristics of the indicator dye prepared in the foregoing example are graphically illustrated in the accompanying FIGURE in the curve designated A. The curve designated B represents the spectral absorption characteristics of 3,3-bis-(3- carboxy-4-hydroxy-l '-naphthyl)naphthalide, i.e., the carboxynaphthol naphthalide of the example without the 6-sulfonamido substituent on the naphthalide ringclosing moiety. This dye was prepared according to steps B, D, and E of the procedure set out above by reacting naphthalaldehydic acid and l-hydroxy-2- naphthoic acid in the presence of p-toluene sulfonic acid to form the 1:1 adduct; reacting the adduct with l-hydroxy-2-naphthoic acid in aqueous base to form the leuco dye intermediate; ionizing the leuco dye intermediate with sodium base; and oxidizing the ionized dye intermediate to yield the indicator dye product.

From reference to the FIGURE, it can be seen that the indicator dye of the present invention absorbs radiation over a broader wavelength range than the same dye without the 6-sulfonamido substituent. Moreover, the dye of the present invention is a more effective absorber of radiation within the broader wavelength range as evidenced by the greater area under the curve and the more box-like shape of the curve.

The pH sensitive indicator dyes of the present invention may be used as optical filter agents in any photographic process including conventional tray processing and diffusion transfer photographic techniques. In such processes, the dye or dyes during development of a selectively exposed photosensitive material will be in a position and in a concentration effective to absorb a given level of non-selective radiation incident on and actinic to the photosensitive material. The dyes may be initially disposed in the film unit, for example, in a layer(s) coextensive with one or both surfaces of the photosensitive layer. Where selective exposure of the photosensitive material is made through a layer containing the indicator dye, then the dyes should be in a non-light-absorbing form until the processing solution is applied. Alternately, the dyes may be initially disposed in the processing composition in their lightabsorbing form, for example, in the developing bath in tray processing or in the layer of processing solution distributed between the photosensitive element and the superposed image-receiving element (or spreader sheet) in diffusion transfer processing. The particular indicator dye or dyes selected should have an absorption spectrum corresponding to the sensitivity of the photosensitive layer, so as to afford protection over the predetermined wavelength range required by the particular photosensitive material employed and should have a pKa such that they are in their colored form, i.e., light-absorbing form at the pH at which the photographic process is performed. Most commercially useful photographic processes are performed under alkaline conditions. Diffusion transfer processes, for example, usually employ highly alkaline processing solutions having a pH in excess of 12.

ln photographic processes where the optical filter agent is retained in a stratum through which the final image is to be viewed, the color of the indicator dye may be discharged subsequent to image formation by adjusting the pH of the system to a value at which the dye is substantially non-light absorbing in the visible spectrum. In photographic processes performed at an alkaline pH, the optical filter agent, such as, a dye or dyes of the present invention are rendered substantially colorless by reducing the environmental pH. In processes where the optical filter agent is removed or separated from the layer containing the final image or retained in a layer that does not interfere with viewing of the final image, it is unnecessary to convert the indicator dye to its non-light-absorbing form, though the color may be discharged if desired.

The concentration of indicator dye is selected to provide the optical transmission density required, in combination with other layers intermediate the silver halide emulsion layer(s) and the incident radiation, to prevent nonimagewise exposure, i.e., fogging, by incident actinic light during the performance of the particular photographic processv It has been found, by interposing neutral density (carbon containing) filters over a layer of titanium dioxide, that a transmission density of approximately 6.0 from said neutral density filters was effective to prevent fogging of a diffusion transfer multicolor film unit of the type described in said US. Pat. No. 3,415,644 having a transparent support layer and an Equivalent ASA Exposure Index of approximately 75, when processed for one minute in 10,000 foot candles of color corrected light, a light intensity approximating the intensity of a noon summer sun. The transmission density required to protect such a film unit under the stated conditions may also be expressed in terms of the system transmission density of all the layers intermediate the silver halide layer(s) and the incident light; the system transmission density required to protect color film units of the aforementioned type and photographic speed has been found to be on the order of 7.0 to 7.2. Lesser levels of optical transmission density would, of course, provide effective protection for shorter processing times, lesser light intensities and/or films having lower exposure indices. The transmission density and the indicator dye concentration necessary to provide the requisite protection from incident light may be readily determined for any photographic process by following the above described procedure or obvious modifications thereof.

Since most commercial photographic processes cmploy photosensitive materials sensitive to and exposable by actinic radiation throughout the visible spectrum, e.g., black-and-white panchromatic silver halide emulsions and multilayer silver halide emulsion elements, it is preferred to use a second dye(s) in conjunction with the subject dye(s) that has a principal absorption in a second and at least partially different predetermined wavelength range such that the combination of dyes will afford protection from non-selective incident actinic radiation over the range of 400 to 700 nm. The second dye employed may be non-color-changing but preferably, is also pH sensitive, i.e., has reversibly alterable spectral absorption characteristics in response to changes in the environmental pH so that it may be rendered light-absorbing or non-light-absorbing as desired. Illustrative of such dyes are phthaleins derived from indoles, such as, indole phthalein. The second dye also may be initially present in the film unit or in the processing composition as discussed above either together with or separate from the subject dyes and subsequent to processing may be removed from the film unit or retained within the film structure, provided it is in a form or position such that it does not interfere with viewing of the image produced.

Dyes may be selected from those described above that are particularly useful as optical filter agents in diffusion transfer processes, for example, those employing composite diffusion transfer photosensitive elements including a film pack or roll wherein superposed photosensitive and image-receiving elements are maintained as a laminate after formation of the final image. Such elements include at least one transparent support to allow viewing of the final image without destroying the structural integrity of the film unit. Preferably, the support carrying the photosensitive layer(s) is opaque and the support carrying the image-receiving layer is transparent and selective photoexposure of the photosensitive layer(s) and viewing of the final image both are effected through the latter support. The final image is viewed as a reflection print, i.e., by reflected light, provided by a reflecting agent initially disposed in the processing composition applied and maintained intermediate the image-receiving and next adjacent photosensitive layer or by a preformed layer or reflecting agent initially positioned intermediate the imagereceiving and next adjacent photosensitive layer. it will be understood that a preformed reflecting layer, while it should be capable of masking the photosensitive layer(s) subsequent to image formation, should not interfere with selective photoexposure of the photosensitive material prior to processing.

When utilizing reflection-type composite film units, the indicator dye or dyes employed as the optical filter agent(s) may be positioned initially in a layer of the film unit, e.g., in a layer between the image-receiving and next adjacent photosensitive layer through which photoexposure is effected provided it is incorporated under conditions, i.e., at a pH such that it will not absorb actinic radiation intended to selectively expose the photosensitive material to form a latent image therein. For example, the optical filter agent may be in a layer coated over either the image-receiving layer or the next adjacent photosensitive layer and should remain substantially non-light-absorbing until a processing composition is applied providing a pH at which the indicator dye is capable of being rapidly converted to its lightabsorbing form to provide light protection when the film unit is removed from the camers. Rather than being initially disposed in the film unit, the indicator dye may be initially present in the processing composition applied intermediate the image-receiving and next adjacent photosensitive layer subsequent to photoexposure. The dye, when initially disposed in the processing composition, will be in its light-absorbing form.

The dyes selected as optical filter agents should exhibit at the initial pH of the processing, maximum spectra] absorption of radiation at the wavelengths to which the film units photosensitive silver halide layer or layers are sensitive, and preferably, should be substantially immobile or nondiffusible in the alkaline processing composition in order to achieve optimum efficiency as a radiation filter and to prevent diffusion of filter agent 1 into layers of the film unit where its presence may be undesirable. Recognizing that the filter agent absorption will detract from image-viewing characteristics by contaminating reflecting pigment background, the selected agents should be those exhibiting major spectral absorption at the pH at which processing is effected and minimal absorption at a pH below that which obtains during transfer image formation. Accordingly, the selected optical filter agent or agents should possess a pKa below that of the processing pH and above that of the environmental pH subsequent to transfer image formation.

As discussed previously, the concentration of indicator dye is selected to provide the optical transmission density required, in combination with other layers intermediate the silver halide emulsion layer(s) and the incident radiation, to prevent nonimagewise exposure, i.e., fogging, by incident actinic light during the performance of the particular photographic process. In the processes where the indicator dye or dyes selected as optical filter agents are used in conjunction with a reflecting agent or agents, the optical filter agents and reflecting agents together should possess the optical transmission density necessary to protect the photosensitive material for the particular photographic process. The optimum concentration of optical filter agent(s) or filter agent(s) together with reflecting agent(s) may be readily determined empirically for each photographic system.

While substantially any reflecting agent may be employed for the layer of reflecting agent, either preformed or applied a component of the processing composition, it is preferred to select an agent that will not interfere with the color integrity of the dye transfer image, as viewed by the observer, and, most preferably, an agent which is aesthetically pleasing to the viewer and does not provide a background detracting from the information content of the image. Particularly desir- 5 able reflecting agents will be those providing a white background, for viewing the transfer image, and specifically those conventionally employed to provide background for reflection photographic prints and, especially, those agents possessing the optical properties desired for reflection of incident radiation.

As examples of reflecting agents, mention may be made of barium sulfate, zinc sulfide, titanium dioxide, barium stearate, silver flake, silicates, alumina, zirconium oxide, zirconium acetyl acetate, sodium zirconium sulfate, kaolin, mica, and the like.

Illustrative of the photographic use of the indicator dyes of the present invention as optical filter agents, a photographic film unit may be prepared by coating, in succession, on a gelatin subbed, 4 mil. opaque polyethylene terephthalate film base, the following layers:

1. a layer of the cyan dye developer l,4-bis-(B- [hydroquinonyl-a-methyl]-ethylamino)-5,8-dihydroxyanthraquinone dispersed in gelatin and coated at a coverage of about 80 mgs./ft. of dye and about 100 mgs./ft. of gelatin;

2. a red-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 225 mgs./ft. of silver and about 50 mgs./ft. of gelatin;

3. a layer of the acrylic latex sold by Rohm and Haas Co., Philadelphia, Pa., U.S.A., under the trade designation AC-6l and polyacrylamide coated at a coverage of about 150 mgslft. of AC-6l and about 5 mgs./ft. of polyacrylamide;

4. a layer of the magenta dye developer 2-(p-[B- nydroquinonylethyl]-phenylazo)-4-isopropoxy-lnaphthol dispersed in gelatin and coated at a coverage of 70 mgs./ft. of dye and about 120 mgs./ft. of gelatin;

5. a green-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 120 mgs./ft. of silver and 60 mgs./ft. of gelatin;

6. a layer comprising the acrylic latex sold by Rohm and Haas Co. under the trade designation 3-15 and polyacrylamide coated at a coverage of about 100 mgs./ft. of B-l5 and about 10 mgs./ft. of polyacrylamide;

7. a layer of the yellow dye developer 4-(p-LB- hydroquinonylethyl]-phenylazo)-3-(N-n-hexylcarboxamido)-l-phenyl-5pyrazolone and the auxiliary developer 4'-methylphenyl hydroquinone dispersed in gelatin coated at a coverage of about 50 mgs./ft. of dye, about 15 mgs./ft. of auxiliary developer and 50 mgs./ft. of gelatin;

8. a blue-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 75 mgs./ft. of silver and about 75 mgs./ft. of gelatin; and

9. a layer of gelatin coated at a coverage of about 50 mgs./ft. of gelatin.

Then a transparent 4 mil. polyethylene terephthalate film base may be coated, in succession, with the following illustrative layers:

1. a 7:3 mixture, by weight, of polyethylene/maleic acid copolymer and polyvinyl alcohol at a coverage of about 1400 mgs./ft.'-, to provide a polymeric acid layer;

2. a graft copolymer of acrylamide and cliacetone acrylamide on a polyvinyl alcohol backbone iii 'a molar ratio of l.:3.2:l at a coverage of about 800 lags-7& to provide a polymeric spacer layer; and

3. a 2:1 mixture, by weight. of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of about 900 mgs./ft. and including about 20 mgsJft. phenyl mer capto tetrazole, to provide a polymeric image-receiving layer.

The two components thus prepared may then be taped together in laminate form, at their respective edges, by means of a pressure-sensitive binding tape extending around, in contact with, and over the edges of the resultant laminate. 10

A rupturable container an outer layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline prcoessing solution comprising:

OH OH Q so -m1 2532 may then be fixedly mounted on the leading edge of each of the laminates, by pressure-sensitive tapes interconnecting the respective containers and laminates,

such that, upon application of compressive pressure to 55 a container, its contents may be distributed, upon rupture of the containers marginal seal, between the polymeric image-receiving layer and next adjacent gelatin layer.

The photosensitive composite film units may be exposed through step wedges to selectively filter radiation incident on the transparent polyethylene terephthalate layer and processed by passage of the exposed film units through appropriate pressure-applying members, such as suitably gapped, opposed rolls, to effecti rupture of the container and distribution of its contents. During processing, the multicolor dye transfer image formation may be viewed through the transparent polyethylene terephthalate layer against the titanium dioxide background provided by distribution of the pigment containing processing composition between the polymeric image-receiving layer and gelatin layer 9 of the photosensitive component. The film unit may be exposed to incident light and the formation of the image may be viewed upon distribution of the processing composition by reason of the protection against incident radiation afforded the photosensitive silver halide emulsion layers by the optical filter agents and by reason of the effective reflective background afforded by the titanium dioxide.

The film unit detailed above is similar to that shown in FIG. 2 and related FIGS. 3 and 4 of aformentioned copending US. Pat. application Ser. No. 101,968. The negative component of the film unit including the photosensitive strata and associated dye-image-forming material; the positive component including the timing, neutralizing and dyeable layers; and the processing composition including its components, such as, the alkaline material and various addenda are described in detail in application Ser. No. 101,968. For conve- 2.0 gms.

nience, the specification of this application is specifically incorporated herein.

Besides the above photosensitive element, dyes of the present invention may be employed in composite photosensitive elements, in general, where the dyeable stratum along with any associated layer may be contained together with the photosensitive strata as a unitary film unit which may be termed an integral negative-positive film unit comprising a negative component including the aforementioned essential layers and a positive component including at least the dyeable stratum in which the color transfer image is to be formed. The essential layers are preferably contained on a transparent dimensionally stable layer or support member positioned closest to the dyeable stratum so that the resulting transfer image is viewable through this transparent layer. Most preferably another dimensionally stable layer which may be transparent or opaque is positioned on the opposed surface of the essential layers so that the aforementioned essential layers are sandwiched or confined between a pair of dimensionally stable layers or support members, at least one of which is transparent to permit viewing therethrough of a color transfer image obtained as a function of development of the exposed film unit in accordance with the known color diffusion transfer processes. It will be appreciated that all of these film units, like the specific one detailed above, may optionally contain other layers performing specific desired functions, e.g., spacer layers, pH-reducing layers, etc.

Examples of such integral negative-positive film units for preparing color transfer images viewable without separation are those described and claimed inaforementioned U.S. Pat. No. 3,415,644 and in U.S. Pats. Nos. 3,415,645, 3,415,646, 3,473,925, and 3,573,043.

In general, the film units of the foregoing description, e.g., those described in the aforementioned patents and/or copending applications, are exposed to form a developable image and thereafter developed by applying the appropriate processing composition to develop exposed silver halide and to form, as a function of de' velopment, an imagewise distribution of diffusible dye image-providing material which is transferred, at least in part by diffusion, to the dyeable stratum to impart thereto the desired color transfer image, e.g., a positive color transfer image. Common to all of these systems is the provision of a reflecting layer between the dyeable stratum and the photosensitive strata to mask effectively the latter and to provide a back ground for viewing the color image contained in the dyeable stratum, whereby this image is viewable without separation, from the other layers or elements of the film unit. As discussed previously, in some embodiments this reflecting layer is provided prior to photoexposure, e.g., as a preformed layer included in the essential layers of the laminar structure comprising the film unit, and in others it is provided at some time thereafter, e.g, by including a suitable light-reflecting agent, for example, a white pigment, such as, titanium dioxide, in the processing composition. As an example of such a preformed layer, mention may be made of that disclosed in the copending applications of edwin H. Land, Ser. Nos. 846,441, filed July 31, 1969, and 3,645 filed Jan. 19, 1970 and now U.S. Pat. Nos. 3,615,421 and 3,620,724, respectively. The reflecting pigment may be generated in situ is disclosed in the copending applications of Edwin H. Land, Ser. Nos. 43,741 and 43,742, both filed June 5, 1970 and now U.S. Pat, Nos. 3,647,434 and 3,647,435 respectively. In a particularly preferred form, such film units are employed in conjunction with a rupturable container, such as, that used above, containing the processing composition having the light-reflecting agent incorporated therein which container is adapted upon application of pressure of distributing its contents to develop the exposed film unit and to provide the light-reflecting layer.

As noted previously, the photographic use of the dyes of the present invention as optical filter agents to prevent post-exposure fogging of a selectively exposed photosensitive elements. While the use of such dyes in composite multicolor diffusion transfer film units is a particularly preferred embodiment of the present invention, these dyes may be used with equally effective results in any photographic process where it is desired to protect a photosensitive material from incident radiation actinic to the photosensitive material within the wavelength range capable of being absorbed by the dye. For example, the subject dyes may be used in conventional tray photographic processing as a component of the processing bath, or they may be present in a layer coextensive with one or both surfaces of a layer of photosensitive material to be processed using conventional tray procedures, provided that they are non-lightabsorbing prior to photoexposure and also subsequent to developing the latent image unless the layer containing the dye is to be removed subsequent to processing. In such procedures, the photoexposed photosensitive material will, of course, be transferred from the camera to the processing bath in the absence of radiation actinic to the material.

The subject dyes also may be employed in diffusion transfer processes where the photosensitive and imagereceiving elements are separated subsequent to the formation of a transfer image or where a spreader sheet is separated from the photosensitive element to reveal a final image in the negative. In addition to the composite diffusion transfer structures described above, the subject dyes may be used with composite diffusion transfer film units where the final image is to be viewed by transmitted light. Also they may be used in composite film units specifically adapted, for example, for forming a silver transfer image, for developing a negative silver image by monobath processing, for obtaining an additive color image, and for obtaining a dye image by the silver dye bleach process which structures are described in detail in aforementioned copending U.S. application Ser. No. 101,968, particularly with reference to FIGS. 10 to 13 of the applications drawings.

Although the invention has been discussed in detail throughout employing dye developers, the preferred image-providing materials, it will be readily recognized that other, less preferred, image-providing materials may be substituted in replacement of the preferred dye developers in the practice of the invention. For example, there may be employed dye image-forming materials such as those disclosed in U.S. Pats. Nos. 2,647,049;

3,443,941; 3,443,943; etc., wherein color diffusion transfer processes are described which employ color coupling techniques comprising, at least in part, reacting one or more color developing agents and one or more color formers or couplers to provide a dye transfer image to a superposed image-receiving layer and those disclosed in U.S. Pat. No. 2,774,668 and 3,087,817, wherein color diffusion transfer processes are described which employ the imagewise differential transfer of complete dyes by the mechanisms therein described to provide a transfer dye image to a contiguous image-receiving layer, and thus including the employment of image-providing materials in whole or in part initially insoluble or nondiffusible as disposed in the film unit which diffuse during processing as a direct or indirect function of exposure.

In view of the foregoing, it will be readily apparent that the subject dyes are useful generally in photographic processes for producing silver, monochromatic and multi-color images using any photosensitive material including conventional and direct positive silver halide emulsions. Depending upon the selected photosensitive material, one or more of the dyes may be used alone or in combination with another optical filter agent, such as another light-absorbing dye, which second dye may be non-color-changing or another pH sensitive dye. If the selected dye or dyes do not possess the desired stability in the processing composition for long term storage therein, they may be initially disposed in the film structure or stored in a doublecompartmented pod or in one of two associated pods separate from the processing solution until such time as the pod(s) are ruptured whereupon the dyes are admixed with the processing solution.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is: l. A compound of the formula:

wherein R, R, R and R each are selected from hydrogen and a hydrogen-bonding group forming a 5-, 6- or 7-membered intramolecular hydrogen-bonded ring with the adjacent OH and being a member selected from hydroxy, carboxy, o-hydroxyphenyl, sulfonamido, sulfamoyl and bis trifluoromethyl carbinol, at least one of R and R and at least one of R and R being hydrogen, and R is a hydrocarbon group containing up to 20 carbon atoms selected from alkyl, phenyl, phenylsubstituted alkyl and alkylsubstituted phenyl.

2. A compound as defined in claim 1 wherein R, R R and R are hydrogen.

3. A compound as defined in claim 1 wherein R and R are hydrogen and at least one of R and R is a hydrogen-bonding group. 7,

4. A compound as defined in claim 3 wherein R is carboxy.

5. A compound as defined in claim 3 wherein R and R are carboxy.

6. A compound as defined in claim 1 wherein R is alkyl-substituted phenyl. V

7. 3,3-bis(3'-carboxy-4-hydroxy-l-naphthyl)-6-ndodecylphenylsulfonamidonaphthalide. 

1. A COMPOUND OF THE FORMULA:
 2. A compound as defined in claim 1 wherein R1, R2, R3 and R4 are hydrogen.
 3. A compound as defined in claim 1 wherein R1 and R4 are hydrogen and at least one of R2 and R3 is a hydrogen-bonding group.
 4. A compound as defined in claim 3 wherein R2 is carboxy.
 5. A compound as defined in claim 3 wherein R2 and R3 are carboxy.
 6. A compound as defined in claim 1 wherein R is alkyl-substituted phenyl.
 7. 3,3-bis(3''-carboxy-4''-hydroxy-1''-naphthyl)-6-n -dodecylphenylsulfonamidonaphthalide. 